What is that!! A R2R guide to common new tank hitchhikers.

[Swede's Reef]

Pods of some kind. Amphipods?

 

[ISpeakForTheSeas]

Trying to figure out what this might be

Yeah, without substantially closer-up pics, I'd guess either some kind of pod or possibly a very small polychaete worm of some kind. Most pods and polychaetes are good to have.

 

[mycoralswontgrow]

Yeah, without substantially closer-up pics, I'd guess either some kind of pod or possibly a very small polychaete worm of some kind. Most pods and polychaetes are good to have.

same assumption i made. i went and dipped a couple other zoas from the same rack and they had some pods on them.

 

[Errrca_Foster]

One of the greatest things about starting a reef tank is getting your live rock in and admiring all the diversity within it. The rock comes to life different creatures. This is a guide that I, along with a very well known critter identifier @KJ , have put together for the new reefer on what these hitchhikers are and whether they're a keeper or to pull them out.

Bristleworm -

Very common good hitchhiker. The jury is out on whether they're beneficial or not. Most consider them a vital part of your clean up crew. The hide within your live rock, coming out to pick up scraps of food and other detritus. Their numbers can become overwhelming based off how much food is available in the tank. If you overfeed, and they have access to an abundance of food, their numbers will increase dramatically. Be careful not to touch as the bristles on the sides of their bodies can be very irritating and cause an allergic reaction in some.


Fireworm -

Bad hitchhiker. Similar to the bristle worm, however if stung by the bristles on this little guy, its 10 times worse. DO NOT TOUCH UNDER ANY CIRCUMSTANCES! If found it is best to remove with a trap.

Pineapple Sponges -

Very common good hitchhiker. These little guys are a type of sponge. They are most commonly found in overflows and in high flow areas of the sump. However, they can sometimes bee seen in shaded areas of your rockwork.

Asterina Starfish -

Another common neutral hitchhiker. Jury is out on these guys as to good or bad. Some people love them, some hate them. They've been rumored to munch on coralline algae. They are also known to multiply very rapidly. Manual removal when seen is best to control their numbers.


Aiptasia -

Bad hitchhiker. This is a type of anemone that multiplies very quickly, and stings and kills anything that gets near it. Depended on how many you have, they're best removed by manually scraping them off the rock, and then using epoxy/superglue/kalk paste over where they were to prevent them coming back. A few predators that you can get for them include the peppermint shrimp, berghia nudibranch, and with a large enough tank, copperband butterflyfish.

Majano -

Bad Hitchhiker. This is another pest anemone that multiplies quickly and stings anything near it. Best removed by manual scraping off and super glue/epoxy/kalk past over its spot. Peppermint shrimp will reportedly consume them as well.

Vermedit Snail -

Very common neutral hitchhiker. They are generally harmless, but can multiply quickly based off nutrients in the tank, and can irritate corals. Manual removal or starving them out by putting a dab of superglue on the end of the tube is best to keep their numbers in check, as well as nutrient control.

Spirorbid Worm -

Very common neutral hitchhiker. These guys are most commonly found in overflows, and high flow areas of your sump. Can multiply very quickly and have been rumored to disrupt equipment such as pumps. Nutrient control keeps their numbers in check.

Ball Anemone -

Common neutral hitchhiker. They are found in shaded areas of live rock, and tend to not bother anything and numbers are kept in check with nutrient control. Are removed by the same means as the aiptasia and majano.

Stomatella Snail -

Very good hitchhiker. These guys are a great clean up crew member. They can be very elusive and most commonly found after lights out and are very fast moving. They feed off different algae in the tank.


Copepod/Isopod/Amphipod -

Very good hitchhikers. Often referred to as simply "pods" These little guys live within your rock work and make great food for your fish and corals. They can be the primary diet of certain mandarins.

Spaghetti Worm -

Good hitchhiker. Commonly found in the sand bed or live rock. They extend out multiple tentacles to catch floating detritus. Good member of your clean up crew.

Hydroids -

Bad hitchhikers. Good news is that they don't tend to live very long and die off on their own as the tank progresses.


Digitate Hydroids

Bad hitchiker- irritates nearby corals


Sponges -

Good hitchhiker. Very common filter feeders. Found in shaded areas of live rock

Serpent And Brittle Starfish -

Good hitchhikers. Are most commonly found by the arms extending out from cracks and holes in rock work. Feed off leftover food and detritus in the tank.

Bobbit Worm -

Very bad hitchhiker. These guys can grow to be very large and can kill fish. Most common means of removal is to remove the entire rock where the worm is housed. Be careful of the pincer teeth at the head of the worm.

Tunicate -

Good hitchhiker. Harmless filter feeder. At first glance looks like a sponge, except it pulses as it takes in and expels water, and reacts to touching it.

Limpet -

Good hitchhiker. Consumes algae. Don't seem to bother anything.

Fleshy Limpet

Neutral hitchiker. Algae grazer, but have been rumored to bother corals.

Slipper Limpet - Neutral hitchiker. Commonly attached to other snail shells. Don't cause any harm to the Snail or other tank inhabitants


Elephant Slug

Good hitchhiker. Algae grazer.

Chiton -

Good hitchhiker. Consumes algae. Does not appear to bother anything.

Peanut Worm -

Good hitchhiker. Lives in live rock and feeds off of extra food and detritus.

Gorilla Crab -

Bad hitchhiker. Can be found in live rock cracks, caves and holes. They are predatory and will hunt your shrimp and inverts. They can also grow rather large.

Benthic Ctenophores -

Been seeing this one pop up more and more lately, so I figured why not add them to the list.
They are a neutral hitchhiker. They mainly filter feed on zooplankton and small particulates in the water. Most commonly referred to as comb jellys.

Red Planaria Flatworm -

Bad Hitchiker. While they don't consume any coral, they can grow in numbers to the point where they smother coral. Caution should be taken as when these die off they release toxins that can wipe out a tank quickly.

Ghost Flatworm -

Neutral hitchiker. Doesn't harm anything. But does consume pods

Acoel Flatworm -

Neutral Hitchiker. Doesn't harm anything, however can grow greatly in numbers quickly

Polyclad Flatworm -

Bad Hitchhiker. Predatory towards clams and coral depended on subspecies.

Pumpkin Flatworm (Waminoa Sp)

Bad Hitchiker. Predatory. Can smother and kill LPS corals.

Acropora Eating Flatworm -

Bad Hitchiker. See name


I did not cover Nudibranch or snails in this thread as there are far to many variations to cover. If you have an unknown, please create a thread or post it in this thread and we'll try our best to ID it for you. If you have any additions to the list please PM me and I'll review it and add to the list.

I’m a newb here (for sw aquariums) and I found two hitchhikers on my live rock. One is for sure an Asterina (letting it live its life for now) and then we found another this morning if anyone knows what it is or called. I tried to lighten the pics to see it better (I’m no photo editor )

 

[nsteinca]

I’m a newb here (for sw aquariums) and I found two hitchhikers on my live rock. One is for sure an Asterina (letting it live its life for now) and then we found another this morning if anyone knows what it is or called. I tried to lighten the pics to see it better (I’m no photo editor )

Looks like palythoas. Could be zoanthids, but the polyp shape and color looks more paly

 

[mikst]

This looks like an asterina starfish to me. It's on the upper left corner of the frag plug, same greenish as the plug. 5 point. An I right in identifying it? This guide says it's neutral.

 

[Reefkeepers Archive]

This looks like an asterina starfish to me. It's on the upper left corner of the frag plug, same greenish as the plug. 5 point. An I right in identifying it? This guide says it's neutral.

It's blurry, but as far as I can tell, yeah. Though there are rare cases where they will eat zoas, but it should be fine.

 

[mikst]

It's blurry, but as far as I can tell, yeah. Though there are rare cases where they will eat zoas, but it should be fine.

Here's a picture of its underside since it's moving around now. Thanks

 

[Crabs McJones]

Here's a picture of its underside since it's moving around now. Thanks

Looks like an asterina star to me

 

[jldb97]

Anyone know what this is on my coral frag? I’ve tried to highlight it; never seen one before

 

[Crabs McJones]

Anyone know what this is on my coral frag? I’ve tried to highlight it; never seen one before

Looks like a tube/fan worm. Cool filter feeder

 

[jldb97]

Looks like a tube/fan worm. Cool filter feeder

Cool thanks for response, I was hoping something harmless!

 

[TD1260]

Thoughts? Thinking bristle worm (the good kind????) Found this one in about 200 pounds of live rock I received tonight so concerned about the rest:/

 

[vetteguy53081]

Thoughts? Thinking bristle worm (the good kind????) Found this one in about 200 pounds of live rock I received tonight so concerned about the rest:/

Bristleworm, yes, Some regard them as with myself a pest while others like them as part of clean up crew. They eat uneaten food and detritus and of course do not touch them with bare hands. I've had some well over a foot long.

 

[EeyoreIsMySpiritAnimal]

Thoughts? Thinking bristle worm (the good kind????) Found this one in about 200 pounds of live rock I received tonight so concerned about the rest:/

Actually, the bright red on the "bristles" of tgecsecond worm might indicate a fireworm. Can you get a picture of its head? Bearded fireworms have a distinct caruncle.
They almost always enter the hobby via harvested live rock.

Edit: the first pic clearly shows a common bristleworm, so if the pics are of the same worm, carry on

 

[TD1260]

Actually, the bright red on the "bristles" of tgecsecond worm might indicate a fireworm. Can you get a picture of its head? Bearded fireworms have a distinct caruncle.
They almost always enter the hobby via harvested live rock.

Edit: the first pic clearly shows a common bristleworm, so if the pics are of the same worm, carry on

Yep same critter in both. I’m going to get some crabs and other goodies to pick through the rock while the tank cycles. Gonna look into traps now. None in my other tanks so won’t cross pollenate!

 

[vetteguy53081]

Yep same critter in both. I’m going to get some crabs and other goodies to pick through the rock while the tank cycles. Gonna look into traps now. None in my other tanks so won’t cross pollenate!

Arrow crab will eat them

Arrow:

 

[TD1260]

Arrow crab will eat them

Arrow:

My concern with the arrow crab is that it may kill some of the additional critters I want to have once the tank is established. Once I buy an animal, I can’t bring myself to get rid of it so I have to think long-term. Just my style sadly. debating whether or not I treat the tank with dewormer since right now it has nothing but sand in live rock in it. Although be at the live rock came with plenty of copepods I naturally dont want to kill off.

 

[Crabs McJones]

Some wrasse are rumored to eat them

 

[vetteguy53081]

My concern with the arrow crab is that it may kill some of the additional critters I want to have once the tank is established. Once I buy an animal, I can’t bring myself to get rid of it so I have to think long-term. Just my style sadly. debating whether or not I treat the tank with dewormer since right now it has nothing but sand in live rock in it. Although be at the live rock came with plenty of copepods I naturally dont want to kill off.

Ive had them and sold them and never had an issue with them going after other inverts. Using Prazipro which is tank safe will also kill them but you then have to vacuum and search for and remove the dead ones